Device for sampling gas within the rotating bowl of a centrifuge

ABSTRACT

The sampling device comprises a stationary axial column adapted to support at least one transfer tube which is joined to a transverse scoop within a sampling chamber. The scoop is displaceable between a withdrawn position in which it is wholly contained within the column and an outwardly-extended position in which it projects from the column as a result of a relative displacement of the tube with respect to said column. By permitting the controlled withdrawal of the scoops into the stationary axial column to which they are connected, the device makes it possible to introduce and remove the column and the scoops through a narrow transfer opening.

[ Jan. 14, 1975 United States Patent Lascoux DEVICE FOR SAMPLING GAS WITHIN THE ROTATING BOWL OF A CENTRIFUGE [75] Inventor: Pierre Lascoux, Plaisir, France [73] Assignee: Commissariata LEnergie Atomique, Paris, France Jan. 10, 1973 ABSTRACT [22] Filed:

[21] Appl. No.: 322,354

The samplmg device comprises a stationary axial column adapted to support at least one transfer tube Foreign Appllcatlon Priority Data which is joined to a transverse scoop within a sampling Jan. 19, 1972 France.............................. 72.01696 chamber. The scoop is displaceable between a withdrawn position in which it is wholly contained within the column and anoutwardly-extended position in which it projects from the column as a result of a relative displacement of the tube with respect to said column. By permitting the controlled withdrawal of the scoops into the stationary axial column to which they are connected, the device makes it possible to intro [56] References Cited UNITED STATES PATENTS duce and remove the column and the scoops through a narrow transfer opening.

FOREIGN PATENTS 0R APPLlCA'llON 9 Claims 3 Drawing mum 95,877

DEVICE FOR SAMPLING GAS WITHIN THE ROTATING BOWL OF A CENTRIFUGE This invention relates to a device for sampling gas within the rotating bowl of a centrifuge and more particularly within two chambers formed at the ends of the bowl which is designed more generally in the form of a cylindrical shell closed by end-walls and mounted for rotation at high speed about its axis.

In centrifuges of known types, different solutions have already been contemplated with a view to carrying out a sampling operation of the kind referred-to above, especially by making use of substantially radial scoops stationarily mounted within the end chambers of the bowl and connected to a hollow column disposed coaxially with the bowl spindle but locked rotationally with respect to the bowl. These scoops withdraw the gas directly from the bowl without preventing the rotation which is necessary for the generation of centrifugal force. In these known designs, the end-walls of the bowl can be detached from the shell of the bowl so as to permit the successive assembly of the stationary and moving portions of the unit and especially of the hollow column which is connected to the sampling scoops. Alternatively, the end-walls can be connected to the shell of the' bowl whilst the scoops remain imprisoned within the sampling chambers, the hollow axial column alone being sometimes removable and connected to said scoops by any suitable means such as screwing or fitting into each other, for example.

However, the known designs just mentioned are subject to a number of disadvantages. In the first case, the assembly of the shell and its end-walls is unreliable and makes it difficult to ensure strict and continuous balancing, especially by reason of the deformations of these components. In the second case, mounting of the axial column on the scoops gives rise to practical difficulties. Moreover, the fact that these scoops cannot. be removed without involving complete destruction of the bowls or the end-walls constitutes a major defect.

The present invention relates to a sampling device which overcomes these disadvantages and permits the controlled withdrawal of the scoops within the stationary'axial column to which they are connected, thereby permitting assembly and disassembly of said column and the scoops through a relatively narrow transfer opening formed in one end-wall of the bowl, the diameter of said opening being appreciably smaller than the transverse dimension of the scoops when these latter are in a position of outward extension with respect to the column itself in order to carry out the desired sampling of gas.

To this end, the device under consideration comprises a stationary column mounted on the axis of the rotating bowl and adapted to carry at least one transfer tube for the sampled gas, said tube being connected to a scoop which is capable of extending transversely within a sampling chamber formed at one end of the bowl. The device is characterized in that said scoop is displaceable between a withdrawal position in which it is wholly contained within the column and an outwardly-extended position in which said scoop projects with respect to said column within the sampling chamber as a result of a relative displacement of the tube with respect to the column.

Preferably, the column is provided with means whereby the scoop which is connected to the transfer tube is locked in the withdrawn position.

In a first embodiment of the invention, the scoop which forms an extension of the transfer tube at that end which penetrates into the bowl through the column is constituted by an elbowed portion of said tube which is disposed in a plane substantially at right angles to the axis of the bowl and terminates in a sampling orifice, the displacement of said scoop between its outwardlyextended position and its withdrawn position being such as to correspond to a rotation of the tube about its axis through a given angle with respect to the column. Preferably, and in order to prevent any vibrations of the scoop which may arise during operation from the rotational motion of the bowl, the scoop is applied in the position of outward extension with respect to the column against a stationary abutment shoulder which is integral with said column, the pressure of application of said scoop against said abutment shoulder being produced by a torsional stress exerted on the tube in that portion of this latter which is located outside the bowl. As an advantageous feature, the column carries a series of parallel tubes each connected to a sampling scoop, said scoops being placed within each of two sampling chambers which are formed at the two ends of the rotating bowl.

In accordance with a further characteristic feature, the ends of the tubes which are remote from the scoops are associated with a locking device which serves to lock said scoops in the outwardly-extended position with respect to the column, said locking device being provided with a sliding yoke which is guided along stationary rails carried by the column and adapted to cooperate with a flat portion formed in the tube, the engagement of said yoke over said flat portion being permitted when the torsional stress which is exerted on the tube and applies the scoop against its abutment shoulder attains the predetermined value. By way of alternative, the torsional stress on the tube is applied by the yoke of the locking device itself, said yoke being progressively displaced under the action of a transverse screw carried by said yoke and applied against a stationary bearing member of the column.

In another embodiment of the invention, the scoop which forms an extension of the transfer tube at one end is constituted by an elbowed duct disposed substantially in a plane which passes through the axis of the tube and terminates in a sampling orifice, the connection between the tube and the elbowed duct being provided by a flexible hose element, the displacement of the scoop between its outwardly-extended position and its withdrawn position being such as to correspond to a displacement of the tube in a direction parallel to the axis of the column so as to cause the sliding motion of the elbowed duct and the flexible hose within a curved guide passage formed within the column and having its opening on the side of this latter. In the same embodiment, the tube is advantageously associated with a locking device for maintaining the scoop in the outwardly-extended position, said locking device being provided with a spacing sleeve which is coaxial with the tube and limits the axial travel of said tube with respect to the column and with a cross-bar or the like which cooperates with a slot formed at the end of said tube.

Further properties of a sampling device as constructed in accordance with the invention will become apparent from the following description of two exemplified embodiments which are given by way of indication without any implied limitation, reference being made to the accompanying drawings, wherein:

FIG. 1 is a diagrammatic longitudinal sectional view in perspective showing a first embodiment of a centrifuge fitted with a sampling device in accordance with the invention;

FIGS. 2a and 2b are longitudinal sectional views of another embodiment, in which FIG. 2a illustrates more especially the lower portion of the sampling device and FIG. 2b is a view to a larger scale showing the upper portion of said device.

In FIG. 1, the reference 1 designates the rotating bowl assembly of a centrifuge having a cylindrical shell 2, the ends of which are closed by two parallel endwalls 3 and 4 respectively. The rotating bowl 1 is driven by any conventional means, not shown, about the axis 2a which corresponds to the axis of the cylinder of the shell 2. Sampling of gas fractions in a centrifuged mixture by means of the high-speed rotation of the bowl 1 is carried out within chambers 5 and 6 which are formed at the end of said bowl and delimited with respect to the end-walls 3 and 4 by means of parallel transverse partitions 7 and 8 carried by the internal surface of the shell 2.

The end-wall 3 of the rotating bowl 1 is provided at the top with a cylindrical annular flange 9 which delimits an opening 10 for providing access to the interior of the bowl, a hollow column 11 being mounted within said opening in coaxial relation with the bowl. Said column 11 supports a series of sampling tubes which are four in number in the exemplified embodiment shown in the drawings and designated respectively on the one hand by the references 14 and 15 and on the other hand by the references 16 and 17 depending on whether said tubes open into the chambers 6 or 5; said tubes extend parallel to the axis 2a of the bowl 1 and are'associated with sampling scoops which will be described in greater detail hereinafter.

Thus, in accordance with the invention, each of the tubes mentioned in the foregoing, for example the tube 14, is connected at the end'oppositeto the portion which passes out of the bowl to a scoop l8 constituted by a portion of said tube which is elbowed in a plane at right angles to the axis 2a, said scoop being provided at the end thereof with a sampling orifice 19 through which the sampled centrifuged gas is permitted to penetrate. In order to ensure positional control of the scoop 18, the tube 14 is capable of carrying out a movement of rotation about its axis within the column 11, with the result that the elbowed portion of the scoop is permitted to move either to an outwardlyextended position as illustrated in full lines or on the contrary to a withdrawn position in which said elbowed portion is accordingly located within the apparent contour of the hollow column 11; this second position as illustrated by the scoop 18a which is associated with the tube 15 is shown in dashed lines.

In order that any possible vibrations arising from aerodynamic excitations of the scoops during highspeed rotation of the bowl should be compensated during operation, said scoops are advantageously applied in the outwardly-extended position against an abutment shoulder such as 20 which is integral with the hollow column 11, the application of the scoop 18 against said abutment shoulder being carried out by subjecting the corresponding tube to torsional prestress. To this end, said tube is provided at the end located outside the rotating bowl and at the end remote from the scoop with a slot 21 which serves to apply torsion to the tube by means of any suitable handling tool and especially a screwdriver and to apply the scoop against its abutment shoulder with the necessary pressure. Moreover, in order that this application pressure should be continuously maintained, the tube 14, for example, is associated with a positional locking device 22 comprising a yoke 23 slidably mounted in rails 24 which are stationarily fixed with respect to the hollow column 11. Said yoke 23 is provided with a slot 25 which is capable of cooperating with a flat portion 26 formed in the oppositely-facing end of the tube, the engagement of said flat portion within the slot of the yoke being possible only when the torsion applied to said tube attains the desired value. It will be readily apparent that a similar locking device is provided for the tube 15 but is not illustrated for the sake of simplicity of the drawing.

The foregoing arrangements which are adopted in the case of tubes 14 and 15, the scoops 18 of which are thus capable of displacement within the sampling chamber 6 are identical in the case of the tubes 16 and 17 having scoops such as 27 and 27a which are shown respectively in the outwardly-extended position and in the withdrawn position and are intended to perform sampling operations within the top chamber 5. It should nevertheless be noted that, taking into account the smaller length of the tubes 16 and 17, the associated locking device which is intended to produce the necessary torsional stress can be designed in a slightly different manner. In particular, said device which is generally designated by the reference 29 may be provided with only one yoke 30 having a slot 31 which is engaged over a flat portion 32 of the tube 17, for example. Twisting of said tube is carried out directly by the yoke 30 by means of an operating screw 33 which cooperates with a stationary bearing member 34 provided in the column 11.

FIGS. 2a and 2b illustrate another alternative embodiment in which is again shown a bowl 40 which rotates about the axis of a shell 41 and is closed by endwalls such as 42. A stationary column 43 is mounted'on the axis of the rotating bowl 40 and carries tubes 44 and 45 connected to sampling scoops which are capable of displacement between a retracted position in which said scoops are completely withdrawn within the column 43 and an outwardly-extended position in which said scoops project outwards from said column near the ends of the bowl. In this alternative form of construction, the tube 44, for example, is connected to a scoop 46 in the form of a tubular duct provided at the end with an orifice 47 through which the gas is sampled. The scoop 46 is connected to the tube 44 by meansof a flexible hose element 48 mounted together with said scoop within a curved guide passage 49 which forms an extension of the tube 44 at the base of the column 43 and terminates in an opening 51 in the lateral surface of said column. The scoop 46 can thus pass out of said opening as a result of a displacement of the tube 44 in a direction parallel to its axis.

There is shown in FIG. 2b a locking device which serves to limit the displacement of the scoops which are connected to each end of the tubes of the support column and in particular their range of outward travel from this latter. The tube 45, for example, is accordingly guided by a collar 52 fitted with a seal 53, the range of translational motion of said tube being limited by means of a spacing sleeve 54 which is coaxial with said tube and against the upper end of which is applied a washer 55. Furthermore, in order to lock the tube rotationally together with the scoop which is mounted at the end of this latter, the upper portion of the tube 45 cooperates with a cross bar 56 which is capable of engaging within a groove 57 formed in the end of said tube; the cross-bar is locked in position by means of a pin 58 fixed on a top end-cap 59 which is secured against the stationary column 43 by means of fixing screws 60.

No matter which form of construction is adopted, there is thus provided a device for sampling gas within a centrifuge bowl in which the outward displacement of sampling scoops can be remote-controlled; the scoops can be returned in a reverse movement to the retracted position in which they are withdrawn into the interior of a column which serves to support said scoops; and the column can be removed from the rotating bowl without requiring any direct work on said bowl and in particular on its end-walls.

Accordingly, the device under consideration has an advantage in that it can be employed with a single-unit bowl which is rigid and cannot be disassembled, and in which the geometry and balancing of the bowl can be checked once and for all in the workshop. Moreover, the assembly of the column and of the scoops carried by this latter is an easy operation; the scoops are also readily interchangeable by means of this device. Finally, a further advantage lies in the fact that the sampling diameter or in other words the extent of outward travel of the scoops can readily be varied without entailing the need to modify these latter in any way.

It must clearly be understood that the invention is not limited to the examples of construction which are more especially described and illustrated in the drawings but extends on the contrary to all alternative forms.

What we claim is:

l. A device for sampling gas comprising a rotating bowl of a centrifuge, a stationary column mounted on the axis of the rotating bowl, at least one transfer tube for the sampled gas, mounted on said column, a scoop connected to said tube and extending transversely within a sampling chamber at one end of the bowl, said scoop being displaceable between a withdrawn position in which it is wholly contained within the column and an outwardly-extended position in which said scoop projects with respect to said column within the sampling chamber and means for providing a relative displacement of said tube with respect to said column.

2. A sampling device according to claim 1, including means mounted on the column for locking the scoop connected to the transfer tube in withdrawn position.

3. A sampling device according to claim 1, said scoop including an elbowed portion of said tube disposed in a plane substantially at right angles to the axis of the bowl and a sampling orifice for said elbowed portion, the displacement of said scoop between its outwardlyextended position and its withdrawn position corresponding to a rotation of said tube about its axis through a given angle with respect to said column.

4. A sampling device according to claim 3, including a stationary abutment shoulder on said column, the scoop being applied in the position of outward extension with respect to the column against said shoulder and means for applying pressure of application of said scoop against said abutment shoulder by a torsional stress on the tube outside the bowl.

5. A sampling device according to claim 1, including a series of parallel tubes in said column, a sampling scoop connected to each of said tubes, said scoops being disposed within each of two sampling chambers at the two ends of the rotating bowl.

6. A sampling device according to claim 5 including means for locking the ends of the tubes remote from the scoops in the outwardly-extended position with respect to the column, said locking means including a sliding yoke, stationary rails carried by the column guiding said yoke and a flat portion in the tube receiving said yoke, said yoke engaging over said flat portion when the torsional stress exerted on the tube applies the scoop against its abutment shoulder and attains a predetermined value.

7. A sampling device according to claim 6, said yoke applying the torsional stress on the tube and a transverse screw carried by said yoke and applied against a stationary bearing member of the column displacing said yoke.

8. A sampling device according to claim 1, said scoop including an elbowed duct disposed substantially in a plane which passes through the axis of the tube said sampling orifice, being disposed at one end of said duct a flexible hose element connecting said tube and said elbowed duct, the displacement of said scoop between its outwardly-extended position and its withdrawn position corresponding to a displacement of said tube in a direction parallel to the axis of the column moving said elbowed duct and said flexible hose within a curved guide passage within the column, said passage on a side of said column.

9. A sampling devi e according to said locking device for maintaining the scoop in the outwardly-extended position including a spacing sleeve coaxial with the tube to limit the axial travel of said tube in one direction with respect to the column, a fixed corss-bar limiting the movement of said tube in the other direction and a slot in the end of said tube engaging said crossbar. 

1. A device for sampling gas comprising a rotating bowl of a centrifuge, a stationary column mounted on the axis of the rotating bowl, at least one transfer tube for the sampled gas, mounted on said column, a scoop connected to said tube and extending transversely within a sampling chamber at one end of the bowl, said scoop being displaceable between a withdrawn position in which it is wholly contained within the column and an outwardly-extended position in which said scoop projects with respect to said column within the sampling chamber and means for providing a relative displacement of said tube with respect to said column.
 2. A sampling device according to claim 1, including means mounted on the column for locking the scoop connected to the transfer tube in withdrawn position.
 3. A sampling device according to claim 1, said scoop including an elbowed portion of said tube disposed in a plane substantially at right angles to the axis of the bowl and a sampling orifice for said elbowed portion, the displacement of said scoop between its outwardly-extended position and its withdrawn position corresponding to a rotation of said tube about its axis through a given angle with respect to said column.
 4. A sampling device according to claim 3, including a stationary abutment shoulder on said column, the scoop being applied in the position of outward extension with respect to the column against said shoulder and means for applying pressure of application of said scoop against said abutment shoulder by a torsional stress on the tube outside the bowl.
 5. A sampling device according to claim 1, including a series of parallel tubes in said column, a sampling scoop connected to each of said tubes, said scoops being disposed within each of two sampling chambers at the two ends of the rotating bowl.
 6. A sampling device according to claim 5 including means for locking the ends of the tubes remote from the scoops in the outwardly-extended position with respect to the column, said locking means including a sliding yoke, stationary rails carried by the column guiding said yoke and a flat portion in the tube receiving said yoke, said yoke engaging over said flat portion when the torsional stress exerted on the tube applies the scoop against its abutment shoulder and attains a predetermined value.
 7. A sampling device according to claim 6, said yoke applying the torsional stress on the tube and a transverse screw carried by said yoke and applied against a stationary bearing member of the column displacing said yoke.
 8. A sampling device according to claim 1, said scoop including an elbowed duct disposed substantially in a plane which passes through the axis of the tube said sampling orifice, being disposed at one end of said duct a flexible hose element connecting said tube and said elbowed duct, the displacement of said scoop between its outwardly-extended position and its withdrawn position corresponding to a displacement of said tube in a direction parallel to the axis of the column moving said elbowed duct and said flexible hose within a curved guide passage within the column, said passage on a side of said column.
 9. A sampling device according to said locking device for maintaining the scoop in the outwardly-extended position including a spacing sleeve coaxial with the tube to limit the axial travel of said tube in one direction with respect to the column, a fixed corss-bar limiting the movement of said tube in the other direction and a slot in the end of said tube engaging said cross-bar. 